1. Field of the Invention
The present invention relates to oven controls and more particularly relates to cooking oven controls which govern both the oven function and the oven temperature by operation of a single manually settable knob or dial.
2. The Prior Art
Cooking ovens generally contain a burner, or heating element, at the bottom of the oven which is operated to heat the oven air for "baking" food and a burner at the top of the oven providing a radiant heating source for "broiling" food. The "bake" burner, whether it be an electric element or a gas burner, is normally cycled "on" and "off" to maintain a predetermined sensed oven air temperature level. In many ovens the "broil" burner is also capable of being controlled thermostatically.
In the past ovens have been provided with dual controls, one, sometimes called a "change over control," for enabling selection of the desired oven function (i.e., baking or broiling), the other for enabling selection of a desired oven air set point temperature. The use of dual controls of the character referred to has had the undesirable effect of increasing the volume occupied by the controls in the oven chassis as well as increasing the cost of the ovens.
Oven controls have been proposed which enable both oven function and oven temperature selection by a single control unit. These control units have had a single control knob or dial which is manually operated to govern the selection of the oven function and to establish the desired oven air temperature to be maintained while that function is performed. Compared to dual controls the single control units have, generally speaking, reduced the amount of space occupied by the controls and have reduced that portion of the oven cost attributable to controls.
Single knob oven controls have employed a knob which is rotatable from an oven "off" position through a range of angular movement during which the bake burner is operated. Within this range of motion the knob is positionable to select any desired oven temperature set point level. When the knob is turned further to approach the limit of its travel remote from the "off" position, operation of the bake burner is terminated and the broil burner is operated.
The prior art controls have been constructed and arranged to enable the maintenance of set point oven temperatures by the broil burner. To accomplish this the knob has been returned from the "broil" section of its travel to a desired oven temperature setting. Whenever the knob is turned to the "off" position the control is reset so that the broil burner is reactivated only when the knob is next turned to the "broil" section of its range of travel.
Additional capabilities have been built into the single knob oven controls. For example, in some installations rapid "preheating" of the oven is desirable and in these ovens the control switches for the bake and broil burners have been related so that when the control is turned "on" to perform a baking function both the broil and bake burners are operated until the sensed oven temperature approaches the set point temperature at which time the "broil" burner is deactivated.
The controls which have been utilized to govern the operation of the ovens have often been difficult to assemble, composed of a relatively large number of parts and, because the amount of space available within the cooking stove chassis is always at a premium, have tended to be undesirably large or "deep", i.e. extend too far into the chassis from the control mounting panel.